i 4 2 OUR INSECT FRIENDS AND FOES 



account of its high price this wax has never been 

 introduced into England, but it is of considerable 

 commercial value both in China and Japan. 



Among the Coleoptera a curious genus of 

 beetles known as " Vesicantia" possess a medical 

 value on account of the strong, irritant fluid they 

 secrete. The Vesicantia are divided into two dis- 

 tinct families, the Molo'idce and the Cantharidce ; 

 some species of the Moloi'dae are used as vesicants 

 and are commonly called " oil beetles," but the 

 Cantharidae are more generally employed as 

 blistering agents. 



The life history of most of the species of the 

 Vesicantia family is very curious ; in addition to 

 the usual metamorphosis these beetles undergo 

 several supplementary changes, which have been 

 called " hyper-metamorphosis " before arriving 

 at the final stage of their existence and becoming 

 perfect insects. We are indebted to that clever 

 and indefatigable naturalist, M. Fabre, for our 

 knowledge of the ways of these remarkable 

 insects. With untiring energy and patience 

 M. Fabre studied the habits of Sitaris muralis 

 (a member of the Moloi'dae family) until he had 

 discovered its complete life history from the egg 

 to the imago. 



The eggs of the Sitaris beetle are laid in the 

 summer-time near to the entrance of a gallery 

 constructed by the hard-working little mason 

 bee ; and in the course of a few weeks the larvae 

 are hatched and crawl forth as tiny, elongated 

 maggots, possessed of six legs each terminating 

 in a sharp claw, while at the tail end their bodies 

 are provided with two horny hooks. 



